Ujama wants to deploy a network device that will allow him to use policy-based controls for email as well as active defenses against phishing attacks before email is delivered to his users. Which of the following devices is best suited to this purpose?

Email security gateways are appliances or software virtual appliances that provide anti-spam, anti-phishing, and other email security–related services. They’re purpose-built to deliver exactly the capabilities that Ujama is looking for. A WAF (web application firewall) is used to protect web applications. DKIM and DMARC are both email security frameworks, but they’re not implemented as appliances themselves.